Boost C++ Libraries

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Function combine

Function combine

The combine function is used to make one range from multiple ranges. The combine function returns a combined_range which is an iterator_range of a zip_iterator from the Boost.Iterator library.

Synopsis

namespace boost
{
    namespace range
    {

template<typename IterTuple>
class combined_range
    : public iterator_range<zip_iterator<IterTuple> >
{
public:
    combined_range(IterTuple first, IterTuple last);
};

template<typename... Ranges>
auto combine(Ranges&&... rngs) ->
    combined_range<decltype(boost::make_tuple(boost::begin(rngs)...))>

    } // namespace range
} // namespace boost

Precondition: For each type r in Ranges, r is a model of Single Pass Range or better.
Return Type: combined_range<tuple<typename range_iterator<Ranges>::type...> >
Returned Range Category: The minimum of the range category of every range r in Ranges.

Example

#include <boost/range/combine.hpp>
#include <boost/foreach.hpp>
#include <iostream>
#include <vector>
#include <list>

int main(int, const char*[])
{
    std::vector<int> v;
    std::list<char> l;
    for (int i = 0; i < 5; ++i)
    {
        v.push_back(i);
        l.push_back(static_cast<char>(i) + 'a');
    }

    int ti;
    char tc;
    BOOST_FOREACH(boost::tie(ti, tc), boost::combine(v, l))
    {
        std::cout << '(' << ti << ',' << tc << ')' << '\n';
    }

    return 0;
}

This produces the output:

(0,a)
(1,b)
(2,c)
(3,d)
(4,e)